The present invention relates to a noncontact IC card that transfers data in a noncontact fashion to and from an external reader/writer, and a method of fabrication thereof.
With a prior-art noncontact IC card, a wound coil that is formed of windings of a thin conductive wire is attached to a card substrate, electronic components such as an IC chip and capacitor are mounted thereon, and then the card substrate is accommodated within a plastic casing; alternatively, a coil-pattern antenna is formed on the card substrate by direct plating or etching, electronic components such as an IC chip and capacitor are mounted thereon, and then the card substrate is sandwiched between plastic sheets or the like.
However, the above described wound-coil type of noncontact IC card of the prior art lacks flexibility and the card itself is thick, which degrades the portability thereof. The thickness of a noncontact IC card is set by ISO regulations to be 0.76xc2x10.08 mm, but most wound-coil noncontact IC cards exceed 1 mm. They are also expensive.
A noncontact IC card with a pattern antenna formed by plating or etching requires a complex method of fabrication and is therefore expensive.
When a small IC chip is mounted, in particular, it is necessary to have a jumper wire that straddles the antenna circuit to ensure contact between the antenna terminals and the IC chip, and that jumper wire must be formed on the rear surface of the card substrate to prevent short-circuiting. Since that jumper wire has to make contact with the antenna circuit on the main surface through through-holes formed in the card substrate, the method of fabrication thereof is complicated. In addition, since this card substrate must be sandwiched between plastic sheets or the like, it is not suitable for mass-production.
If it is necessary to have a number of windings of the antenna coil, to ensure communications reliability, an antenna circuit is formed on each side of the card substrate, or the substrates, each having an antenna circuit have to be superimposed one after another and the end portions at the antenna circuits have to be connected by through-holes, so the method of fabrication thereof is complicated.
The objective of the present invention is to provide a noncontact IC card that can be made thinner and also inexpensive, and a method of fabrication thereof.
The present invention relates to a noncontact IC card comprising: a card substrate; an IC chip provided on one surface of the card substrate; an antenna circuit provided on the same surface of the card substrate as the IC chip and having a pair of antenna terminals, one antenna terminal being connected to the IC chip; an isolation layer provided so as to cover a portion of the antenna circuit; a connection layer provided on the isolation layer and having a pair of end portions, one end portion being connected to the IC chip and the other end portion being connected to the other antenna terminal; and a protective layer provided on top of the card substrate, for protecting the IC chip, the antenna circuit, and the connection layer, and the connection layer.
Another aspect of this invention applies to a noncontact IC card wherein the antenna circuit and the connection layer are formed by printing with a conductive ink; and the isolation layer is formed from an insulating ink.
A further aspect of this invention applies to a noncontact IC card which further comprises a capacitor connected to the antenna circuit, and provided on the same surface of the card substrate as the antenna circuit.
A still further aspect of invention applies to a noncontact IC card wherein the capacitor has a first electrode layer formed of a conductive ink, a dielectric layer formed of an insulating ink and provided on the first electrode layer, and a second electrode layer formed of a conductive ink and provided on the dielectric layer.
A yet further aspect of this invention applies to a noncontact IC card which further comprises an additional antenna circuit on the antenna circuit through an additional isolation layer.
An even further aspect of this invention applies to a noncontact IC card wherein the protective layer has a first protective layer disposed on the card substrate side and a second protective layer provided on the first protective layer.
Yet another aspect of this invention applies to a noncontact IC card wherein an aperture allowing the passage of the IC chip is provided in the first protective layer.
Still another aspect of this invention applies to a noncontact IC card wherein the first protective layer is a thermo-adhesive sheet.
This invention also applies to a noncontact IC card which further comprises a pattern layer on outer sides of the card substrate and the protective layer.
This invention further applies to a noncontact IC card wherein the capacitor is disposed so as to be connected to one antenna terminal of the antenna circuit and one end portion of the connection layer.
This invention still further applies to a noncontact IC card wherein the capacitor is connected to one antenna terminal of the antenna circuit by a first linking layer and to one end portion of the connection layer by a second linking layer.
This invention even further applies to a noncontact IC card wherein the antenna circuit and the first electrode layer of the capacitor are disposed on the same plane surface, the isolation layer and the dielectric layer of the capacitor are disposed on the same plane surface, and the connection layer and the second electrode layer of the capacitor are disposed on the same plane surface.
This invention also applies to a method of fabricating a noncontact IC card having a card substrate with an IC chip, an antenna circuit, and a capacitor provided on the card substrate, in which the IC chip and the antenna circuit are connected by a connection layer on an isolation layer provided on said antenna circuit; wherein the fabrication method comprises a first conductive printing step of printing the antenna circuit and a first electrode layer onto predetermined locations of one surface of the card substrate; an insulation printing step of printing an isolation layer onto at least part of the antenna circuit that was formed by the first conductive printing step and also printing a dielectric layer on the first electrode layer that was formed by the first conductive printing step; and a second conductive printing step of printing a connection layer on the isolation layer that was formed by the insulation printing step and also printing a second electrode layer on the dielectric layer that was formed by the insulation printing step, to form the capacitor.
Finally, this invention also applies to a method of fabricating a noncontact IC card, further comprising a step of providing a protective layer on top of the card substrate, for protecting the IC chip, the antenna circuit, the isolation layer, and the connection layer.